Going commando is the practice of not wearing underwear under one's outer clothing. The term is theorised to be related to the much earlier term "going regimental", which refers to wearing the kilt military style, that is, without underwear.
Kilts have been traditionally worn without undergarments since their use as part of Scottish military uniform, leading to the invention of such expressions as "going commando" or"go regimental" or "military practice" for wearing no underwear. On the Western Front during the First World War, some Sergeants Major reportedly had mirrors tied to the end of golf clubs or walking sticks to inspect up and under the kilt at parade inspection. However, in 1940 the kilt was retired from combat due to the vulnerability of bare skin to chemical agents, although it was retained as the formal dress uniform of the regiments. In the 1950s, kilted soldiers on parade would be checked by the Sergeant Major using a mirror on the barracks floor. In 1997, a Black Watch soldier received wide press exposure, because of windy conditions during a military ceremony in Hong Kong.